Add files related to B(s)0 -> L0 L0bar hh decays
See merge request !1438 (merged)
(cherry picked from commit fd6d8f10)
6957dc74 Add files related to B(s)0 -> L0 L0bar hh decays d6cc2d78 Bug fix c025d0b7 Fix evttype 1caa6ac3 More update 4e1af0c0 Use CDecay